It is current practice to improve color and flavor attributes in cocoa matrices, i.e. nibs, liquor, or powder by increasing the natural pH value of about 5.5 by alkalizing. Typical cocoa liquor contains >50% fat, 12% protein residues, 9% cellulose, 6% polyhydroxyphenols, 7% starch (amylose; amylopectin 70:30; w/w), 4% pectins, 2% water, organic acids, and a range of minor constituents such as phospho- and glycolipids.
Cocoa alkalization practices mostly proceed on a know-how basis. In principle, alkalization consists in mixing defined volumes of aqueous alkali with a cocoa product. Such a treatment modifies flavor and color attributes by increasing the natural pH value in cocoa. The addition of alkalizing solution provokes known (e.g. color and flavor) and unknown changes in the cocoa matrix. Different types of alkalized liquors are pressed to obtain a particular cocoa powder for target food products. In special cases, excess water is used to obtain a wet alkalized cocoa liquor variant. For unknown reasons, such a variant happens to produce excellent wettability effects on the reconstitution of powdered and agglomerated cocoa drinks in aqueous media. In this context, improved wettability is hypothesized to depend on several criteria: the extent of functional changes induced by wet alkalization in cocoa starch granules, the subsequent behavior of modified starch during agglomeration of different ingredients that constitute the powdered beverage and also, factor-dependent effects in the final matrix of agglomerated powder containing several interacting ingredients.
In general, starch granules exothermically absorb water at ambient temperature. This water uptake is reversible. A sufficient temperature increase triggers an endothermic process that leads to starch swelling, concomitant leaching of amylose, and irreversible gelatinization. In principle, the occurrence of the aforementioned process is possible in cocoa liquor due to the presence of about 7 wt-% of native starch.
In addition, it is well known that cocoa products contain endogenous phospholipids. For instance, Fincke-A and Knopp-M (1977) Phosphatide content of cocoa products and raw materials of the chocolate industry, Gordian 77:288-292 found that phospholipids averaged 3.7 g/kg, i.e. about 4.9 mmol/kg in fifteen different cocoa liquors (coefficient of variation 11%).
Published papers indicate that endogenous phospholipids impair starch swelling in general. Becker-A, Hill-S E, Mitchell-J R (2001), Relevance of amylose-lipid complexes to the behaviour of thermally processed starches, Starch/Stärke 53:121-130 showed that phospholipid-amylose-complexes form insoluble films on the surface of starch granules. Such films delay water transport into the granules and prevent starch swelling. In this context, anti-swelling effects are thought to occur in starch during wet alkalization of cocoa liquor in the presence of excess phospholipids. Non-swelling starch is thought to be an anti-wettability factor in instant cocoa beverages. In theory, such starch is unable to scavenge migrating fat in powdered cocoa matrix. In addition, minimized starch swelling and excess phospholipids could contribute to enhanced retrogradation, as reported by Singh-N, Singh-J, Kaur-L, Sodhi-N S, Gill-B S (2003) Morphological, thermal and Theological properties of starches from different botanical sources, Food Chem 81:219-231. Retrograded starch and its hydrophobicity are presumed to be additional anti-wettability factors.
For the purpose of this specification, the term “wettability” should be understood to mean the ability of the cocoa-based powder to dissolve in foodgrade liquids within a reasonable period of time. Wettability is the drowning period measured in seconds for an appropriate amount of powdered beverage that is added as a single dose into an aqueous medium such as milk of specified volume of defined freshness, temperature and composition.
The term “cocoa product”, as used in this specification, means a product obtained from cocoa beans after roasting and grinding. Examples for such cocoa products are cocoa liquor and cocoa powder.
There are reasons to hypothesize that cocoa contains enough native (endogenous) phospholipids to interact with starch in situ, especially during factor-dependent effects of alkalization, agglomeration with other ingredients and storage of the final product. In theory, the molar concentration of phospholipids in cocoa is much higher compared to starch based on equi-ponderal amounts. Cocoa fermentation frees these phospholipids from their carrier lipoproteins for uncontrolled phospholipid-starch interactions. Free phospholipids and their amphipathic, i.e., hydro- and lipophilic nature are believed to enhance the penetration of ambient moisture into the cocoa matrix. Increased moisture is hypothesized to trigger uncontrolled anti-wettability effects during a recurrent exposure of instant cocoa beverages to ambient air and subsequent storage.
The anti-wettability effects are manifold involving native phospholipids and the starch matrix both present in the cocoa product. They are presumed to be related to insufficient cocoa starch swelling and insufficient amylose leaching and starch retrogradation. In addition, moisture penetration and starch retrogradation are likely to cause uncohesiveness in the matrix of agglomerated particles that combine cocoa with other food ingredients. Such destablized agglomerates are prone to splitting into hydrophobic sub-units, especially during handling.
It is therefore an object of the invention to improve the cocoa product for obtaining defined and non-fluctuating wettability effects in powdered cocoa beverages.
It is another object of the invention to provide a cocoa product having defined functional properties in instant beverages exposed to destabilizing factors such as ambient moisture and prolonged storage.